The scale on a map is 6cm : 1km. If two cities are 60cm apart on the map, what is the actual distance in km between the two cities?
Explanation: The scale means that every 6cm on the map corresponds to an actual distance of 1km. A distance of 60cm on the map is the same as 10 $\cdot$ 6cm. The actual distance between the two cities is 10 $\cdot$ 1km, or 10km.